Open the glovebox. Along the top edge of the glovebox measure and mark spots 2 1/2" to the left and right of the latch. Using a drill bit that is slightly smaller than the treads of your screws, drill holes when you made the marks. Tighten a screw in both holes. The screws will clamp the glovebox tighter against the vent panel behind it.

Close your glovebox. Notice the lack of a gap. Slap your forehead for not doing this a long time ago! 8)